+ fs-proc-task_mmu-indicate-pm_file-for-pmd-mapped-file-thp.patch added to mm-unstable branch

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The patch titled
     Subject: fs/proc/task_mmu: indicate PM_FILE for PMD-mapped file THP
has been added to the -mm mm-unstable branch.  Its filename is
     fs-proc-task_mmu-indicate-pm_file-for-pmd-mapped-file-thp.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-proc-task_mmu-indicate-pm_file-for-pmd-mapped-file-thp.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: fs/proc/task_mmu: indicate PM_FILE for PMD-mapped file THP
Date: Fri, 7 Jun 2024 14:23:52 +0200

Patch series "fs/proc: move page_mapcount() to fs/proc/internal.h".

With all other page_mapcount() users in the tree gone, move
page_mapcount() to fs/proc/internal.h, rename it and extend the
documentation to prevent future (ab)use.

... of course, I find some issues while working on that code that I sort
first ;)

We'll now only end up calling page_mapcount() [now
folio_precise_page_mapcount()] on pages mapped via present page table
entries.  Except for /proc/kpagecount, that still does questionable
things, but we'll leave that legacy interface as is for now.

Did a quick sanity check.  Likely we would want some better selfestest for
/proc/$/pagemap + smaps.  I'll see if I can find some time to write some
more.


This patch (of 6):

Looks like we never taught pagemap_pmd_range() about the existence of
PMD-mapped file THPs.  Seems to date back to the times when we first added
support for non-anon THPs in the form of shmem THP.

Link: https://lkml.kernel.org/r/20240607122357.115423-1-david@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240607122357.115423-2-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Lance Yang <ioworker0@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/proc/task_mmu.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/proc/task_mmu.c~fs-proc-task_mmu-indicate-pm_file-for-pmd-mapped-file-thp
+++ a/fs/proc/task_mmu.c
@@ -1522,6 +1522,8 @@ static int pagemap_pmd_range(pmd_t *pmdp
 		}
 #endif
 
+		if (page && !PageAnon(page))
+			flags |= PM_FILE;
 		if (page && !migration && page_mapcount(page) == 1)
 			flags |= PM_MMAP_EXCLUSIVE;
 
_

Patches currently in -mm which might be from david@xxxxxxxxxx are

revert-mm-init_mlocked_on_free_v3.patch
mm-memory-move-page_count-check-into-validate_page_before_insert.patch
mm-memory-cleanly-support-zeropage-in-vm_insert_page-vm_map_pages-and-vmf_insert_mixed.patch
mm-rmap-sanity-check-that-zeropages-are-not-passed-to-rmap.patch
mm-update-_mapcount-and-page_type-documentation.patch
mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type.patch
mm-zsmalloc-use-a-proper-page-type.patch
mm-page_alloc-clear-pagebuddy-using-__clearpagebuddy-for-bad-pages.patch
mm-filemap-reinitialize-folio-_mapcount-directly.patch
mm-mm_init-initialize-page-_mapcount-directly-in-__init_single_page.patch
fs-proc-task_mmu-indicate-pm_file-for-pmd-mapped-file-thp.patch
fs-proc-task_mmu-dont-indicate-pm_mmap_exclusive-without-pm_present.patch
fs-proc-task_mmu-properly-detect-pm_mmap_exclusive-per-page-of-pmd-mapped-thps.patch
fs-proc-task_mmu-account-non-present-entries-as-maybe-shared-but-no-idea-how-often.patch
fs-proc-move-page_mapcount-to-fs-proc-internalh.patch
documentation-admin-guide-mm-pagemaprst-drop-using-pagemap-to-do-something-useful.patch





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